Re: Latest on fixing PRN01 (SVN49)

From an earlier topic:

On Jun 19, 9:45 pm, HIPAR <captc...@xxxxxxxxxxx> wrote:
A report from the front lines:

http://sidt.gpsworld.com/gpssidt/Latest+News/The-SVN-49-Story-What-We...

On Jun 19, 7:10 pm, Mike Jr <n00s...@xxxxxxxxxxx> wrote:

Obviously nobody can go 'up there' and disconnect the L5 transmitter
from the antenna farm so yes, the root problem cannot be fixed.

My guess is the 'work around' will adjust the navigation message
parameters that estimate the ionospheric time delay. There's a user
equipment equation that accepts these parameters and the satellite
elevation and azimuth as variables.

--- CHAS

Chas,
I am rusty on my end user nav algorithms but if I remember correctly,
ionospheric delay is calculated every ten days or so and applies to
the entire constellation. It is useless for correcting a single
bird. A more useful approach may be to look at turning off coarse
acquisition on the L1 signal. Makes IIR-20(M) useless to the low end
users who rely on it for, well, coarse acquisition. But it will not
hurt them either.

--Mike Jr

Your correct, they aren't going to adjust the ionospheric
parameters.

The Air Force no longer includes the PRN01 satellite error in its
daily performance report. I occasionally checked it during the last
two weeks (or so) before they stopped reporting it. PRN01 was well
below a meter so their 'tuning' appears to be working. As a
navigator, I'd be happy with those results but those who rely on GPS
for precision survey should be skeptical until the testing is
complete.

My experience with 'work arounds' has been they restore basic
functionality but often leave or introduce higher order problems ..
like the initial attempts to computer correct the images from Hubble
Space Telescope.

--- CHAS



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